Omicron Hydrae

Omicron Hydrae
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Hydra
Right ascension 11h 40m 12.78970s[1]
Declination −34° 44′ 40.7733″[1]
Apparent magnitude (V) 4.70[2]
Characteristics
Spectral type B9 V[3]
U−B color index −0.20[2]
B−V color index −0.08[2]
Astrometry
Radial velocity (Rv)+5.9[4] km/s
Proper motion (μ) RA: −43.24[1] mas/yr
Dec.: −1.61[1] mas/yr
Parallax (π)7.27 ± 0.16 mas[1]
Distance449 ± 10 ly
(138 ± 3 pc)
Absolute magnitude (MV)−0.99[5]
Details[6]
Mass3.56±0.04 M☉
Luminosity309 L☉
Temperature10,495 K
Rotational velocity (v sin i)160 km/s
Other designations
ο Hya, CD−34° 7610, FK5 439, HD 101431, HIP 56922, HR 4494, SAO 202695.[7]
Database references
SIMBADdata

Omicron Hydrae (ο Hya) is the Bayer designation for a solitary[8] star in the equatorial constellation Hydra. At one time it bore the Flamsteed designation 25 Crateris, but this is no longer used by astronomers so as to avoid confusion.[9] With an apparent visual magnitude of 4.70,[2] this star is visible to the naked eye. Based upon an annual parallax shift of 7.27 mas,[1] it is located around 449 light years from the Sun.

This is a B-type main sequence star with a stellar classification of B9 V.[3] It has completed an estimated 98.4%±1.1% of its lifetime on the main sequence. With 3.56[6] times the mass of the Sun, it radiates 309 times the Sun's luminosity from its outer atmosphere at an effective temperature of 10,495 K.[6] The rate of spin is relatively high, with a projected rotational velocity of 160 km/s.[6]

  1. ^ a b c d e f Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Mermilliod1986 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Houk1982 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference fk6_3 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  6. ^ a b c d Cite error: The named reference Zorec2012 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Wagman1987 was invoked but never defined (see the help page).